This invention relates to devices for performing mechanical operations such as piercing, punching and forming on a workpiece and more particularly to an improved device for applying mechanical forces to the workpiece in a self-equalizing fashion.
Mechanical operations such as piercing, punching, shape forming and resistance welding are common to many industrial fabrication processes. In many instances, it is desirable or necessary to perform such operations on a relatively thin section workpiece which is already finished to proper size and material specifications. For example, it may be necessary to pierce or punch a hole or a group of holes in a metal bracket which is stamped, finished and heat treated prior to the piercing or punching operations. Under these circumstances, it is important to avoid any significant deformation or reshaping of the workpiece during the piercing or punching operation. This can be achieved through the use of "self-equalizing" fabrication devices or machines; i.e., a device or machine which engages and applies equal forces to the opposite sides of the workpiece during the mechanical operation so that undesirable inelastic deformation is avoided.
These are many prior art devices which are capable of accomplishing mechanical operations in a self-equalized fashion such, for example, as the devices disclosed in U.S. Pat. Nos. 3,008,032, 3,396,260, and 4,098,161. Each of those patents disclose apparatus capable of performing one or more work operations on a workpiece in a self-equalized fashion so as to avoid undesirable inelastic deformation of the workpiece during the work operations.
These specific prior art devices, as well as other similar prior art devices of the self-equalizing type, tend to involve a very complicated construction and therefore tend to result in a high initial manufacturing cost as well as a high maintenance cost. Also, by virtue of their bulk and complexity, these prior art devices tend to be difficult to mount in certain orientations so that their usability in a universal sense is severly limited.